October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Amas de galaxies Emission non thermique comme traceur de la formation et de lévolution M. Arnaud CEA - Service dastrophysique Saclay

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR X-ray thermal - diffuseRadio synchrotron - diffuse - steep ( >1) Chandra Sun et al, 02VLA 1.4GHz Clarke & Ensslin, 01 LS X-ray/radio emission: thermal and non-thermal components Hot plasma (T~2-10 keV) Relativistic electrons (~1-100 Gev) Magnetic Field ( G) IC e- on CMB NT X-ray Bacchi et al 03 halo relic A 1914 SKA LOFAR

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Jones et al, 03 Ritchie & Thomas, 02 Cluster hierarchical formation => Shocks (heat the gas at T virial ) Radio halos/relics detected in un-relaxed (merger) clusters only Problem: ~Mpc size but t life ~ years << t diffusion Recent creation or (re) acceleration by a mechanism at cluster scale Several Models - Thermal electrons accelerated by shocks /turbulence - Non thermal electrons (from above or from AGN/Winds) re-accelerated - Secondary electrons from inelastic collisions of NT protons with ICM Origin and acceleration of the relativistic electrons?

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Non thermal e- creation and acceleration mechanism not understood! Diagnostic information on the hierarchical formation process probe the physics of merger events (shocks, turbulence, redistribution of energy …) probe the ICM magnetic field tracer of merger/formation history Possible impact on cosmological parameters estimate (from N(M) or f gas ) May contribute to the overall pressure Mass higher than estimated from the HE equation and P therm only Why study the NT cluster component ? Need (new) radio observations combined with X-ray information

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Govoni et al, 04 Constraints on models density (radio maps) and energy (radio spectra) distribution of NT electrons compared to that of thermal electrons (X-ray) Radio- X-ray comparison for individual clusters (I) A 520 A 773 Radio versus kT map Probably mostly acceleration by turbulence

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR A665 Markevitch & Vikhlinin, 01 Feretti et al, from 330 MHz/1.4 GHz Strong(er) constraints given by spectral index maps Flattening in region affected by merger mergers do supply energy to radio halo No connection to the (weak M ~2) shock re-acceleration by turbulence Extend to much larger cluster samples Radio map ( / S rad ) versus X-ray map (ne/kT/P/S) sensitive multi imaging XMM/Chandra Radio- X-ray comparison for individual clusters (II)

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Radio- NT X-ray comparison for individual clusters halo relic Fusco-Femiano et al, 00 A2256/Beppo-Sax Clarke &Ensslin, 01 Global spectrum => ambigous Spatially resolved spectroscopy Radio: degenerate information on B, NT e- + Faraday Rotation (B, Te-) B in few directions + Hard X-ray : IC (NT e-) break the degeneracy e.g. LOFAR + SIMBOL-X (luminous clusters) LOFAR + XMM ? (low mass systems where IC/thermal higher) SIMBOL-X ( ~2012)

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Statistical studies (I): correlations with global properties Govoni et al, 01Feretti, 05 and ref therein; Bacchi et al, 03 Giovannini et al, 06 Open questions: Do all clusters with a recent merger have halos/relic? Do ALL clusters have a radio halo ? What is the most relevant X-ray quantity and what is the slope/dispersion/evolution of the correlations => quantitative test of models We need: X-ray data: exist (XMM/chandra follow-up of ROSAT samples; XMM serendipitous surveys) Much higher sensitivity radio survey/ follow-up

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Jeltema et al 05 Chandra Buote 01 Statistical studies (II): correlations with dynamical state The frequency/properties of radio halos is expected to evolve with z … a test of structure formation and merger physics …. Correlation with departure from relaxation High z clusters are dynamically younger (as expected in hierarchical scenario) also combination with SZ (Planck) data ….

October 27, 2006 Monique ARNAUD Atelier du PNC: Cosmologie avec SKA et LOFAR Bacchi et al 03 Komissarov & Gubanov 94 Detailed combined X-ray/radio spectro imagery Physics of hierarchical cluster formation (shocks, turbulence, particles acceleration, B amplification etc…) LOFAR: adapted to steep spectrum well matched spatial resolution SKA: more sensitive higher v capability: aging of e- NB: combining with hard X-ray (e.g. SIMBOL-X) part. interesting.. Discovery of new relics/halos and statistical properties (correlation with X-ray/SZ) and evolution with z again constraints on model PLUS tracer of cluster formation LOFAR (and SKA?): survey capability ! A 1914 SKA LOFAR CONCLUSION